This photo of a cactus on fire, taken by Fountain Hills, Ariz. resident Marianne Abrahamson, went viral on Facebook.

PHOENIX -- It’s 113 degrees in Phoenix today, and that’s in the shade. There’s all the usual descriptions: Hot enough to fry an egg, hotter than hell, and all the "It's so hot …" bad jokes.

But I just saw a new one with photographic evidence: “It’s so hot, the saguaros are catching fire.”

This photo is floating on several Facebook pages. At first I thought it was Photoshopped. Saguaros don’t catch fire. They are made up of 80-90 percent water. They can lose 60 percent of their water and survive.

They may blow up when hit by lightning, but they don’t burn. (Yes, dried-out saguaro skeletons burn, but this one appears to be live.)

The most likely explanation is that this isn’t actually a cactus, but a cell tower built to look like a cactus. Companies do that to make them a little less obtrusive. And the towers do catch fire.

As a journalist there are several questions about this original photo: the location, the circumstances, was it really a saguaro?

On the other hand, it is 113 degrees (did I mention that’s in the shade?) and people are talking about the heat. But even if it’s 133 degrees (in the shade), saguaros do not spontaneously combust.

So while I await the answers to my questions, I’ll share the “Burning Cactus” photo.